Bernoulli Effect Smoke Draft Vent Assembly

ABSTRACT

A crown-like structure sits atop a chimney or smokestack as a specially formed chimney cap wherein passing air is required to take a somewhat convoluted path, providing a Bernoulli effect to improve smoke emission draft. Like at least two of its predecessors, the crown has two roof-like canopies, one within the other, each having a series of curved, bent strips separated to permit the wind-flow to pass through. As a departure from the past, the number of sets of strips, or leaves, within each canopy is raised to optimize performance, the preferred number thereof being three.

CROSS-REFERENCE TO RELATED APPLICATIONS

This instrument, filed under 37 CFR 1.53(b) and 1.78 invoking theprovisions of 35 U.S.C. 120, is a Continuation in Part of presentlycopending application Ser. No. 11/492,232 entitled “High Wind Bio-MassCap”, filed Jul. 25, 2006.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

Chimney Draft Systems; Emission Ducts

2. Description of Related Art

Occasionally a descriptive term in this application may be shortened soas to recite only a part rather than the entirety thereof as a matter ofconvenience or to avoid needless redundancy. In instances in which thatis done, applicant intends that the same meaning be afforded each mannerof expression. Thus, the term first canopy venting leaf (11) might beused in one instance but in another, if meaning is otherwise clear fromcontext, expression might be shortened to venting leaf (11) or merelyleaf (11). Any of those forms is intended to convey the same meaning.

The term attach or fasten or any of their forms when so used means thatthe juncture is of a more or less permanent nature, such as might beaccomplished by nails, screws, welds or adhesives. Thus it is statedherein that in many instances, both canopies (1, 2) are respectivelyattached to the assembly's collar (3). A connection in which an objectwould be easily removed from another is described by the word emplace aswhere it is stated that preferably, where both (3, 400) arecylindrically shaped, the collar (3) is emplaced upon a smokestack(400). Employment of the words connector join or any of their forms isintended to include the meaning of any of those terms in a more generalway.

The word comprise may be construed in any one of three ways herein. Aterm used to describe a given object is said to comprise it, therebycharacterizing it with what could be considered two-way equivalency inmeaning for the term. Thus, it is stated that the subject matter hereofcomprises an assembly featuring a specially shaped venting assembly,meaning that the latter is in fact the former and the former, thelatter. The term comprise may also be characterized by what might beconsidered one-way equivalency, as when it is stated herein thatpreferably, welds comprise the leaf-to-collar attachment means (34).This use of the word has a generic sense to it. That is, a weld willalways be leaf-to-collar attachment means (34) but leaf-to-collarattachment means (34) may be a weld in one case but something else-nutsand bolts, for instance—in another. However, the word comprise may alsobe used to describe a feature which is part of the structure orcomposition of a given object. Thus, it is said the collar (3) comprisesdiameter sufficient for axial connection to the smokestack (400). Themeaning in the respective cases is clear from context, however.Accordingly, modifying words to clarify which of the three uses is theintended one seem unnecessary.

Terms relating to physical orientation such as top or bottom, upper orlower, upwards or downwards, refer to the positioning of an object inthe manner in which it would be typically oriented for use or viewing.Assemblies of the sort addressed herein are positioned at the top of thesmokestack (400), the first vent canopy (1) is spoken of as theuppermost one and the venting leaves (11, 21) are connected to thecollar (3) at their (11, 21) lower and outer ends. References to airfoilsurfaces herein, ante, also share these descriptive characteristics.These terms of orientation should be interpreted to represent respectiveaspects or dispositions of members of the assembly in a consistentmanner—even if it were, for example, held upside down in certaininstances.

The term axially disposed as used herein denotes a relationship betweena point of reference upon a first object with a second configured so asto comprise an axis wherein the first's point of reference is lined upor aligned with the axis of the second. The assembly is, thus, said tobe axially disposed upon a smokestack (400) and the assembly's collar(3), beneath the respective vent canopies (1, 2).

Chimney caps of one configuration or another have been with us for sometime. It is probably fair to say that all of them have provided somedegree of usefulness wherein the focus has generally been upon keepingrain out of the chimney while allowing the rising smoke to escape. Lessattention was paid to enhancing the passage of air through the vents soas to provide a proper smoke draw but even that has not been completelyoverlooked. The science of gas emission through orifices, pores orsuitably designed openings in general has only reached the stage—so tospeak—this past 25 years or so. Engineers, having observed theefficiency with which oxygen-carbon dioxide exchange occurs throughexquisitely formed stomata of leaves borrowed from nature in someinstances. Just the right size or shape of opening permits thesought-after optimum level of performance. It is certainly true, forexample, that kitchen gas ranges have benefitted from that enterprise.Numerous industrial applications along that line undoubtedly exist

There is a distinction relative to the application of a chimney orsmokestack (400) venting system. Furnace, wood stove or fireplacearrangements which heat ambient air within the structure to be heatedand then pass the burned byproduct or smoke up the stack (400) to theoutside are identified as one-way heating systems. Those which admit airfrom the outside into the heating chamber, heat it and thereby warm theinterior of the structure—adding it to the ambient air, as it were—andthen, like the other, pass the smoke upward to the outside are two-wayheating systems. The distinction is important in designing what ispositioned atop the chimney or smokestack (400). Two-way systems entaila more complicated design because they must assure the incoming air doesnot interfere with that which is outgoing and vice-versa. Ventilatingsystems dedicated to simplicity—particularly those which are configuredto accommodate the passing wind in a particular way—are most properlyconstructed for one-way heating arrangements only.

Long now in the public domain is U.S. Pat. No. 538,366 issued to Cooper,comprising a four-piece assembly of bent sheet metal to create a crownattached to the chimney or smokestack(400) top. Following along, U.S.Pat. No. 4,103,600 issued to Bridge provided a simple partiallyoverlapping arrangement of two bent wide strips of metal positioned withrespect to one another to permit a somewhat isolated passage for smoketherethrough. Even before the Bridge assembly, however, U.S. Pat. No.3,826,181 issued to Schrade addressed the benefits of what he called“optimum aerodynamic performance” wherein a partial vacuum accommodatedthe wind-flow. The Schrade assembly comprised two crown systems—outerand inner—in each of which two bent strips interconnected to providedomed structures connected to the smokestack (400) at their lower outerends. The crown systems were radially alternated with reference to oneanother so that the passage of air therethrough was convoluted to somedegree; thus contributing to the aerodynamically efficient feature ofthe assembly, now extant for more than 30 years. U.S. Pat. No. 4,325,291issued to Paynton, et al also exhibited that configuration in general,appearing to encompass the workable features of Schrade. Both employ theradially disposed alternation referred to supra, and as an incidentalmatter, both also confer a hinged character upon one of the strips sothat it can be lifted up for access into the interior.

One might be tempted to think that little can be done in the way ofrevision to improve those designs. Not so, however, experience hasdemonstrated that systems employing not merely two but three or moreintersecting venting leaves in each of two generally concentric canopieswork substantially better than merely two of them to provide a muchenhanced Bernoulli effect with the passing wind.

The reason for improved emission in specially configured assemblies ismost properly attributed to what has been identified as the Bernoullieffect wherein, for a specially shaped object moving through the air orsituated so as to permit the passage of moving air (601) over it suchthat relative motion was along an airflow vector (600). The motion wasobserved to create a partial vacuum at a point of relativediscontinuity—such as the upper declining curve of an airfoil (500). Inaircraft, this partial vacuum site—referred to herein as a sector oflower pressure (620)—was observed in conjunction with what is referredto herein as a sector of higher pressure (610) beneath the airfoil (500)to provide an upward force vector (700) providing what was generallyrecognized as “lift”, such that the forward moving aircraft remained inthe air. To explain, it was seen the moving air (601), separating overthe top and bottom of the airfoil (500) took two paths to rejoin at aposterior point—that is, the respective bulks of separated air (601)necessarily merged with one another to continue the stream. That air(601) moving over the curved surface of the airfoil (500) required alonger path and, thus, moved faster than the air (601) passing along therelatively straightened surface of the airfoil's (500) underside—thesector of higher pressure (610) addressed supra. The greater velocity ofthe uppermost air(601) provided the partial vacuum. Essentially the sameeffect was later demonstrated by Venturi wherein the air (601) passingthrough a constriction in a tubular pathway was observed to accelerate,creating—as expected—the partial vacuum.

While the prior art has made some strides along the foregoing lines,certain performance improving configurations yet remain to be providedto fulfill the expectations of the avid exerciser.

BRIEF SUMMARY OF THE INVENTION

A crown-like assembly is shaped to sit atop a chimney flue or smokestacksuch that the rising smoke from a heating system or fireplace belowenters its underside. Emission of the smoke is aided by the passage ofwind though openings in the crown.

The crown comprises a first—or outer—canopy (1) and as well as an innerone (2) disposed so that the first (1) envelopes the second (2). The two(1, 2) are separated somewhat to allow the wind to pass through. Eachcanopy (1, 2) comprises a number of strips curved, bent and joinedgenerally at their centers to form the uppermost part of the crown andfastened downwards at their ends to a ring-like collar (3) which fitsover the smokestack (400). It is, of course, this curved bentconfiguration which provides the crown-like appearance.

Thus, the second—or inner—canopy is contained within the first—orouter—canopy, each with the strips—or venting leaves (11, 21), asidentified herein—so arranged as to provide partially diverted anddivided pathways for the entering wind. Most importantly, thedisposition, number, size and configuration of the leaves (11, 21) issuch as to increase the velocity of the air or wind therein, creatingthe desired Bernoulli effect, supra. So constructed and emplaced, theassembly enhances considerably the emission of the smoke from and, inturn, that of the combustion of, the burning system below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Solid lines in the drawings represent the invention. Dashed linesrepresent either non-inventive material, that not incorporated into aninventive combination hereof and which may be the subject of anotherinvention, or that which although so incorporated, lies beyond the focusof attention.

FIG. 1 is a perspective view of a version of the Bernoulli effect smokedraft vent assembly wherein both canopies (1, 2) comprise bolts and nutsas interleaf attachment means (14, 24).

FIG. 2 depicts an exploded view of the assembly

FIG. 3 illustrates an exploded view of a vent canopy variant—in thiscase, of the first (1), although actually representative of either (1,2).

FIGS. 4 and 5 represent overhead views, respectively, of the first andsecond vent canopies (1, 2).

FIG. 6 demonstrates the Bernoulli effect upon an airfoil (500),exhibiting airflow (601) and the associated vectors (600).

DETAILED DESCRIPTION OF THE INVENTION

The subject matter hereof comprises an assembly featuring a speciallyshaped venting structure designed to sit atop the smokestack (400) of afireplace or the like. It is intended to work not as a two-way ventingsystem but only as a one-way one, supra.

The overall assembly adopts the benefits of the Bernoulli effect,comprising a pair of vent canopies (1, 2)—a first vent canopy (1) and asecond thereof (2). Each (1, 2) comprises three or more venting leaves(11, 21, respectively) which are disposed to cross one another (11, 21)proximate their centers. Preferably, the leaves (11, 21) as members ofeach set thereof (11, 21, respectively) are fastened together at thatsite—that is, the members of the set of first canopy venting leaves (11)would be joined to one another(11) and those of the second canopy set(21), respectively, to one another (21). The connections for those (11)of the first canopy (1) are made by first canopy interleaf attachmentmeans (14) and those (21) of the second canopy (2), by second canopyinterleaf attachment means (24). Attachment means (14, 24, respectively)may comprise merely bolts and nuts.

Both canopies (1, 2) become attached to a collar (3) also comprised bythe assembly. To that end, each venting leaf (11, 21) comprises at itsends (11, 22, respectively) an embracing flange (12, 22). The ventingleaves (11, 21) are disposed to curve downward so that the embracingflanges may be attached to the collar (3) by suitable leaf-to-collarattachment means (34).

The attachment means (34) may comprise nuts and bolts fastened throughattachment orifices (35) disposed in the flanges (11, 21). It ispreferred welds comprise the means (34), however.

The arrangement of the canopies (1, 2) is such that the first ispositioned a short distance—usually an inch or two—above the second sothat the flow of air between them (1, 2) is not impeded. The amount ofspacial separation may depend, of course, upon the assembly's size. Itmay, therefore, be properly stated in shorthand parlance that the firstvent canopy (1) is disposed to overlie the second (2) in separationtherefrom (2).

In most arrangements, the smokestack or chimney flue (400) upon whichthe collar (3) is connected is cylindrically shaped, although othercross-sectional configurations may be extant. In most cases, therefore,the collar (3) will also be cylindrically shaped for its (3) properconnection to the smokestack (400). It is conceivable that a collar (3)may be disposed in some manner upon a smokestack (400) of non-matchingconfiguration. Certainly, the preferred arrangement entails emplacementor other connection of a cylindrically shaped collar (3) upon acylindrically shaped smokestack (400). A number of ways to accomplishthis are known. Where acceptable, the collar may be configured with aninternally disposed shoulder to allow it to be slipped into place aroundthe exterior of the smokestack (400). In many instances, emplacement ofthat sort may meet all of the needs considered. However, if desired,attachment may be adopted for connection. In any event, it isappropriate to state that the collar (400) comprise diameter sufficientfor axial connection upon a smokestack (400).

In attaching the venting leaves (11, 22) to the collar (400), it ispreferred those (21) of the second canopy (2)—necessarily the smaller ofthe two (1, 2) by reason of its (2) disposition below and, therefore,within the encompassing first canopy (1)—be set in place beforeattaching those (11) of the first (1). Attachment arrangement of therespective embracing flanges (12, 22) may, of course, be made upon thecollar (3) in any convenient manner and at any selected site, so long asspaces for air passage are left between the curved venting leaves (11,21). However, it is preferred by far that the second canopy's embracingflanges (22) be spaced around the collar (3) to allow room for those(12) of the uppermost first canopy (1) disposing the attachment pointsof the embracing flanges in an alternate fastening arrangement. Thus,the flanges (21, 22) would encircle the collar (3) in every-otherfashion—a second canopy flange (22); then, a first canopy flange (12); asecond canopy flange (22) again; next, another first canopy flange (12);and so on. Experience has demonstrated that, so long as not less thanthree venting leaves (11, 21) for each canopy (1, 2) are incorporatedwithin the assembly, this preferred arrangement, herein designated oneof angular offset array, to be one providing an improved airflow throughthe leaves (11, 21). It may, thus, be said as a matter of preferencethat by reason of the relative attachment sites of the venting leaves(11, 21) upon the collar (4), those (11) of the first canopy (1) bedisposed in angular offset array from those (21) of the second canopy(2).

To take matter a step further, however, it is even more acceptable ifall-around spacing of the attachment sites be even instead of irregular.It would, therefore, be stated as a matter of greater preference thatthe central angle between each pair of adjoining venting leaves (11, 21)equals that between each other pair thereof (11, 21) and that theangular offset array of the first canopy's venting leaves (11) withrespect to those (21) of the second (2) be regular such that each firstcanopy venting leaf (11) bisects the central angle between a pair ofadjoining venting leaves (21) of the second canopy (2).

By reason of the common attachment site of the embracing flanges aroundthe collar (400), it necessarily follows that the collar (400)occupies—at least in approximation—a centered position vis-a-vis thecanopies (1, 2) and it may, therefore, be properly stated that thecollar (400) is axially disposed below the vent canopies (1, 2).

Because the first vent canopy (1) overlies and more or less envelopesthe second (2) in relative configuration, its leaves (11) are obviouslylonger than those (21) of the second (2). While it is not essential theventing leaves (11, 21) of the respective canopies (1, 2) be equal inlength—that is, for all of the first canopy's leaves (11) to compriseequal length with respect to each other (11) and all those (21) of thesecond canopy' (2) to so comprise, it is again more acceptable for suchto be the case. It would, therefore, be properly stated as anothermatter of preference that the venting leaves (11, 21) of the respectivevent canopies (1, 2) be equal in length to one another (11, 21,respectively).

The disposition of three sets of venting leaves (11, 21) for each canopy(1, 2) in the manner presented herein, supra, provides a highlyefficient Bernoulli effect draft vent for the exiting smoke. Applicantis as yet unaware of the reason why such sets of three—as opposed to alesser number—provide those results. Each of the sets of three providethree paired side-by-side openings. Although it is a matter ofspeculation, the diversion of wind entering a given pair of the threesectors to one side and the other—the right and left—through theremaining two pairs thereof may provide just the optimum Bernoullieffect velocity to accomplish the assembly's intended purpose. As thusfar observed, assemblies with three such sets of leaves (11, 21) arealso even preferred over a greater number thereof (11, 21) andundoubtedly more economical to manufacture.

1. A Bernoulli effect smoke draft vent assembly comprising a first ventcanopy; a second vent canopy; and a collar; each canopy comprising threeor more venting leaves disposed to cross one another proximate theircenters; the first vent canopy disposed to overlie the second inseparation therefrom; the venting leaves of the first canopy disposed inangular offset array from those of the second canopy; the collar axiallydisposed below the vent canopies and comprising diameter sufficient foraxial connection upon a smokestack; the venting leaves further disposedto curve downward and further configured at their ends with embracingflanges, wherein the embracing flanges are attached to the collar. 2.The Bernoulli effect smoke draft vent assembly according to claim 1wherein by reason of the relative attachment sites of the venting leavesupon the assembly's collar, those of the first canopy are disposed inangular offset array from those of the second canopy.
 3. The Bernoullieffect smoke draft vent assembly according to claim 1 wherein thecentral angle between each pair of adjoining venting leaves equals thatbetween each other pair thereof and the angular offset array of thefirst canopy's venting leaves with respect to those of the second isregular such that each first canopy venting leaf bisects the centralangle between a pair of adjoining venting leaves of the second canopy.4. The Bernoulli effect smoke draft vent assembly according to claim 1wherein the width of all venting strips is equal throughout theirrespective lengths.
 5. The Bernoulli effect smoke draft vent assemblyaccording to claim 1 wherein the venting leaves of each canopy areconnected to one another by interleaf attachment means.
 6. The Bernoullieffect smoke draft vent assembly according to claim 1 wherein the collaris cylindrically configured.
 7. The Bernoulli effect smoke draft ventassembly according to claim 5 wherein the interleaf attachment meanscomprises welds.